Apparatus for making an antenna for wire transponders

ABSTRACT

An apparatus for making an antenna for wire transponders of electrically conductive material, comprising at least one depositing device for depositing said wire on a substrate placed on a support element, said at least one depositing device and said substrate being movable with respect to each other; said support element being movable along directions parallel to at least two axis of a Cartesian reference system. A method for making an antenna comprising providing a substrate intended to receive said antenna, providing a lamina or wire of electrically conductive material wound on at least one reel, unwinding said lamina, or said wire from said at least one reel, pressing said lamina, or wire, on a surface of said substrate by means of at least one pressing element, fixing said lamina, or wire, to said substrate, separating, by means of at least one cutting device a stretch of lamina, or wire, fixed to said substrate from the remaining lamina, or wire, wound on said at least one reel, said substrate being movable with respect to an assembly comprised of said at least one reel, said at least one pressing and said at least one cutting device, along at least one direction substantially parallel to an axis of a Cartesian reference system.

This application is the National Phase of PCT International ApplicationNo. PCT/IB2006/000156, filed 27 Jan. 2006. PCT/IB2006/000156 claimspriority to IT Application No. MO2005A000017, filed 28 Jan. 2005. Theentire contents of these applications are incorporated herein byreference in their entirety.

The present invention relates to a method and an apparatus for makingantennas for RFID transponders, i.e. transponders for radiofrequencyidentifying devices.

RFID transponders consist of two essential parts, the so-called antenna,made as a coil in conductive material and an integrated circuitconnected to the two ends of the antenna. Amongst the conductivematerials with which the antenna can be constructed, copper wire coveredwith an insulating glaze is increasingly used today.

Apparatuses are known for making antennas in copper wire that depositand fix the wire onto a substrate that is then used in the subsequentprocesses. Nevertheless, these apparatuses have a high cost/productivityratio.

They are in fact constituted by a certain number of heads, normally six,each of which is supplied by a reel of glazed copper wire and depositsthe wire on a substrate, normally in PVC. These heads move, drawing withthe wire the pattern of the antenna and attaching the wire to thesubstrate by means of a vibrating hammer that follows the head in themovement thereof. The substrate either has to be of a material thatsoftens with the heat generated by the vibrating hammer, retaining thewire, like PVC, or has to be previously coated with a product thatperforms the same function.

The heads that are thus constructed are relatively complex and heavymechanisms, which means that both for economic questions and forquestions of inertia to motion, the number of heads applicable to anapparatus is relatively small. This causes a very high cost/productivityratio.

In addition transponders RFID UHF are known, that is transpondersoperating at frequencies higher than 800 MHz (UHF), in which the antennais a dipole antenna made of a lamina of electrically conductivematerial, for instance metallic material.

It is known in the state of art to make dipole antennas for RFIDtransponders starting from a lamina of electrically conductive materialcoupled with a flexible substrate; the profile of the dipole is cut onthe lamina and, subsequently, the electrically conductive materialoutside the cut profile is removed, the electrically conductive materialremaining on the flexible substrate constituting the dipole antenna.

Such a method requires the use of expensive apparatuses for making thecut of the profile of the antenna and, in addition, the electricallyconductive material removed during production of the antenna is wastematerial, which implies a further increase of costs. Finally, theflexible substrate must consists of a material which is not damagedduring the cutting operations of the profile of the antenna, which mayinvolve considerable mechanical or thermal stresses for the substrate.This need limit the materials which may be used for the flexiblesubstrate and require a selection of said materials depending on themethod used to cut the profile of the antenna.

Another known method provides for obtaining the dipole antenna byprinting the antenna on a flexible substrate using electricallyconductive inks.

Also this method involves comparatively high costs; in addition theantennas made of electrically conductive inks have an electricconductivity substantially lower than the conductivity of antennas madeof laminas of electrically conductive material. The lower conductivityinvolves performances that are qualitatively lower than the performancesof antennas made of laminas of electrically conductive material.

The present invention aims to provide an apparatus and a method formaking antennas for RFID transponders that are relatively cheap andenable high productivity with moderate costs.

According to a first aspect of the present invention there is providedan apparatus for making an antenna for wire transponders of electricallyconductive material, comprising at least one depositing device fordepositing said wire on a substrate, said at least one depositing deviceand said substrate being movable with respect to one another,characterised in that it comprises a support element for said substrate,said support element being movable in directions parallel to the axes ofa Cartesian reference system.

Owing to the provision of a substrate for the support movable accordingto the axes of a Cartesian reference system, it is possible to keep theat least one depositing device stationary with respect to said threeaxes. This allows the amount of masses in motion to be keptsubstantially constant, independently of the number and the mass of thedepositing devices used, which makes possible a considerable increase inproductivity with respect to the apparatuses known from the state ofart.

The at least one depositing device may be made rotatable with respect toan axis perpendicular to the element supporting the substrate. Thismakes possible to optimize the deposition of the wire on the substrate.

According to another aspect of the present invention a method isprovided for making an antenna for transponders, comprising depositing awire in electrically conductive material on a substrate according to apreset pattern, fixing said wire to said support, characterised in thatit comprises, before said depositing, applying to the outer surface ofsaid wire an adhesive substance suitable for assuring the fixing of saidwire on said substrate.

Owing to this aspect of the invention it is possible to fix in a simple,rapid and cheap manner the wire to the substrate, furthermoresignificantly simplifying the structure of the depositing means.

In fact, it no longer being necessary to perform hammering of the wireto ensure adhesion thereof to the substrate, the overall dimensions,weight and costs of the depositing means are significantly reduced.

According to a further aspect of the present invention a method isprovided for making an antenna comprising providing a substrate intendedto receive said antenna, providing at least one lamina, or wire, ofelectrically conducive material wound on a reel, unwinding said at leastone lamina, or wire, from said reel, pressing said lamina, or wire, on asurface of said substrate by means of a pressing element, fixing saidlamina, or wire, of electrically conductive material to said substrate,separating by means of a cutting device a portion of said lamina, orwire, fixed to said substrate from the remaining lamina, or wire, woundon said reel, said substrate and an assembly comprised of said reel,said pressing element, and said cutting device being movable withrespect to one another.

Owing to the invention, it is possible to obtain on a substrate in asimple and economical way wire antennas having whatever shape, or dipoleantennas having arms of whatever shape, for instance a rectilinearshape, a zig-zag shape, a curvilinear shape, or a combination of saidshapes.

The realization does not require expensive apparatuses, because, forinstance, for realizing the dipole antenna it is enough a reel fromwhich the lamina of electrically conductive material may be unwound, aplane mobile with respect to the reel for supporting the substrate, apressing element for pressing on the substrate the lamina ofelectrically conductive material unwound from the reel and a cuttingdevice for cutting the lamina of electrically conductive material.

Alternatively, it is possible to keep stationary the plane supportingthe substrate and make the assembly comprised of reel, pressing elementand cutting device mobile with respect to said plane.

The invention will now be disclosed with reference to the attacheddrawings, in which:

FIG. 1 is a schematic frontal view of an embodiment of an apparatusaccording to the invention;

FIG. 2 is the section II-II of FIG. 1;

FIG. 3 is a schematic front view of a further embodiment of an apparatusaccording to the invention;

FIG. 4 is an enlarged schematic detail of FIG. 3;

FIG. 5 is a schematic frontal view of an apparatus according to theinvention provided with a plurality of depositing means;

FIG. 6 is a schematic perspective view of an example of a way of makingan antenna according to the invention;

FIG. 7 is a perspective view of an example of a further way of making anantenna according to the invention;

FIG. 8 is a perspective view of an example of a still further way ofmaking an antenna according to the invention;

FIG. 9 is a side view of FIG. 6;

FIG. 10 is a side view of a variation of the example of a way of makingan antenna illustrated in FIGS. 6, 7 and 9;

FIG. 11 is a schematic view of a production system for antennasaccording to the invention;

FIG. 12 to 15 illustrate some examples of shapes of dipole antennasobtainable with the method according to the invention.

With reference to FIG. 1, an apparatus 1 for making a transponderantenna according to the invention comprises a support structure 13, forexample in the shape of a portal, comprising a pair of fixed uprights 14and a vertically movable crosspiece 15. To the crosspiece 15 a device 6is coupled for depositing a wire 7 in electrically conductive material,for example a glazed copper wire, on a substrate 8 deposited on asupport element 9.

The device 6 comprises a body 10 having a first guide element 11 at anupper end of the body 10 for guiding the wire 7 and a second guideelement 12 which guide the wire at a lower end of the body 10, at whichthe wire is deposited on the substrate 8.

The support element 9 is fixed to a first sliding element 16, forexample driven by a first linear actuator (not shown) cross-fixed to asecond sliding element 17, driven by a second linear actuator (which isnot shown either), the movement of the sliding elements 16 and 17occurring in two directions that are perpendicular to one another on aplane perpendicular to the vertical movement of the crosspiece 15. Themovement of the support element 9 makes possible to obtain thetransponder antenna without the device 6 for depositing the wireperforming translation movements in a plane parallel to the surface ofthe substrate 8. This reduces substantially the masses that have to bemoved during the deposition of the wire 7. In fact, during thedeposition of the wire 7, the translation movements needed to draw theprofile of the antenna are performed only by the support element 9, withthe substrate 8 thereon, whilst the device 6 does not perform anytranslation movement. Therefore, an apparatus 1 according to theinvention may be provided with a high number of devices 6, withoutconsiderably increasing the masses in motion of translation during thedeposition of the wire, the only increase of the masses in motion oftranslation depending, if necessary, on an increase of the dimensions ofthe support element 9. This allows the productivity of the apparatus 1according to the invention to be increased as compared with theproductivity of apparatus known from the state of art.

Advantageously, the device 6 for depositing the wire 7 may be maderotatable with respect to an axis perpendicular to the surface of thesubstrate 8. This allows the deposition of the wire to be optimized inthe portions of the antennas in which there is a change of direction ofthe wire 7.

In a variation of the embodiment illustrated in FIG. 1 rather thanmaking the device 6 for dispensing and depositing the wire 7 verticallymovable by means of the motion of the crosspiece 15, it is possible tomake the support 9 vertically movable, for instance by making the secondsliding element 17 vertically movable. This makes possible to furtherreduce the masses in motion in the apparatus according to the inventionand, as a consequence, to increase further the productivity.

The adhesion of the wire 7 to the substrate 8 may be obtained byapplying in advance an adhesive substance on the substrate 8, or byusing a vibrating hammer associated with the device 6, as it is knownfrom the state of art.

In FIG. 3 another embodiment of an apparatus 1 according to theinvention is illustrated comprising a support structure 2, for instanceshaped as a portal, provided with a pair of uprights 3 and a crosspiece4. On the crosspiece 4, in a direction substantially parallel to a firstaxis of a Cartesian reference system, a slide 5 is slidable, with whicha device 6′ is coupled for depositing a wire 7 in electricallyconductive material, for example a glazed copper wire, on a substrate 8arranged on a support element 9′. The device 6′ comprises a container10′ inside which a quick setting adhesive substance 10 a (FIG. 4) isfed, capable of assuring a quick adhesion of the wire 7 on the substrate8, a guide element 11′ for guiding the wire 7 into the container 10′ anda dispensing spout 12′ through which the wire 7 is deposited on thesubstrate 8 to obtain an antenna for a RFID device.

The container 10′ is fixed to the slide 5, slidable on the crosspiece 4.The crosspiece 4 is in turn slidable vertically in relation to theuprights 3, i.e. in a direction substantially parallel to a second axisof said Cartesian reference system. The support structure 2 is madeslidable, for example on guides that are not shown in a direction thatis perpendicular to the plane of the FIG. 1, i.e. in a direction that issubstantially parallel to a third axis of said Cartesian referencesystem. When the wire 7 comes into contact with the substrate 8 theadhesive means that covers the external surface of the wire causes theadhesion thereof to the substrate 8. When the wire 7 comes into contactwith the substrate 8 the adhesive substance that covers the externalsurface of the wire causes the adhesion thereof to the substrate 8. Theforce of adhesion of the adhesive substance is chosen so that, in thepresence of a corresponding horizontal movement of the substrate 8 inrelation to the depositing device 6′, the portion of wire 7 a adheringto the substrate 8 exercises on the rest of the wire 7, withoutdetaching itself from the substrate 8, sufficient traction to cause theescape of further wire 7 from the dispensing spout 12′. Duringdepositing of the wire 7 on the substrate 8, the slide 5 moves along thecrosspiece 4 and the portal 2 moves along the support plane thereof, ina direction perpendicular to the direction of the movement of the slide5, to trace the profile of the antenna, whilst the crosspiece 4regulates the distance of the dispensing spout 12 from the substrate 8.

In FIG. 3, the apparatus 1 according to the invention has been shownwith a single device 6′ for dispensing and depositing the wire 7,mounted on the slide 5. It is understood that the apparatus 1 maycomprise a plurality of devices 6′, each of which is mounted on arespective slide 5 slidable on the crosspiece 4 of the portal 2.

The device 6′ may be used also with the embodiment shown in FIGS. 1 and2.

Furthermore, the portal 2 may comprise a plurality of crosspieces 4, oneach of which a plurality of slides 5 is mounted, each with therespective device 6′ for dispensing and depositing the wire 7.

Also in the embodiment of the invention shown in FIGS. 1 and 2 theportal 13 may comprise a plurality of crosspieces 15, on each of which aplurality of devices 6 for dispensing and depositing the wire 7 isfixed.

The embodiment of the invention illustrated in FIGS. 1 and 2 enablesgreater speed of depositing of the wire 7 in relation to the embodimentof the invention illustrated in FIG. 3, because during depositing of thewire on the substrate 8 the portal 13 and the dispensing devices 6remain in a fixed position, whereas the support 9 on which the substrate8 is placed moves in two directions that are substantially perpendicularto one another so that the wire 7 is deposited on the substrate 8according to the preset route of the antennas to be made. As the mass ofthe support 9 and of the sliding elements 16 and 17 is significantlyless than the mass of the devices 6′, of the respective slides 5 and ofthe portal 2 that are moved in the embodiment of the invention disclosedin FIG. 1, the movements of the support 9 can be made at significantlygreater speed than the movements of the portal 2 and of the slides 5,which enables a significant increase in productivity.

Furthermore, the number of depositing devices 6 can be increased withoutlimits, without increasing the moving mass. For example, by using asheet measuring 70×100 cm, to produce transponders of the size of creditcards, up to 121 transponders can be made simultaneously, instead of the6 that are currently producible with the known prior-art apparatuses.

Further examples of realizing the method of making antennas according tothe invention are illustrated in FIGS. 6 to 14.

The antenna may be made using a metallic lamina 19, which is unwoundfrom a reel 18, is pressed on the surface of a substrate 8 (FIG. 10) bya pressing element 22, for instance a pressing roller, and is cut by acutting device 23.

As an alternative, the antenna may be made using a metallic wire 19 a,which is unwound from a reel 18 a, is pressed on the surface of thesubstrate 8 by the pressing element 22 (FIG. 6) and cut by the cuttingdevice.

If a dipole antenna is intended to be made, a metallic lamina 19 will beused having a width equal to the width of the arms of the dipole antennato be made, for instance the arms B1 a, B2 a; B1 b; B2 b; B1 c; B2 c; B1d, B2 d of the dipole antennas A, B, C, D, respectively, illustrated inFIGS. 11 to 14, for instance a width of some millimeters and a thicknessof some microns. The substrate 8 on which the antenna has to be formedmay be arranged on a support element, which is made mobile along twodirections perpendicular with each other and parallel to the surface ofthe support on which the substrate 8 is arranged, in a way quite similarto the way previously described with reference to FIGS. 1 and 2. Theassembly comprised of the pressing roller 22, the cutting device 23 and,possibly, the reel 18, is made rotatable around an axis perpendicular tothe plane of the surface of the substrate 8 and passing through thepoint in which the pressing roller 22 presses the lamina on thesubstrate 8.

In the event of an antenna made with a wire 19 a (FIG. 6), the reel 18 amay be kept stationary, so that only the assembly comprised of thepressing roller 22 and the cutting device 23 is made rotatable around anaxis perpendicular to the plane of the surface of the substrate 8 andpassing through the point in which the pressing roller 22 presses thelamina on the substrate 8.

The adhesion of the lamina 19, or wire 19 a, to the substrate 1 may beobtained in various ways:

by applying in advance on the wire 19 a, or on the face of the lamina 18intended to come in contact with the substrate 8, an adhesive substancewhich, after drying, may be revived by supplying energy, for instance athermoplastic adhesive substance;

by applying in advance on the face of the lamina 18 intended to come incontact with the substrate 8 a so-called “pressure sensitive” adhesivesubstance, that is a substance which activates when the lamina 19 ispressed onto the substrate 8 by the pressing roller 22; in this case,the face of the lamina opposed to the face on which the adhesivesubstance has been applied is protected by a layer of anti-adhesivesubstance, for instance a layer of silicone, or by an anti-adhesiveremovable film, in order to prevent superimposed turns of lamina 19 onthe reel 18 from adhering to each other;

by applying an adhesive substance on the substrate 8 immediately beforeor during the deposition of the lamina 19, or wire 19 a, onto thesubstrate 8.

When dipole antennas such as the antennas illustrated in FIGS. 12 to 14are realized, during deposition of the lamina 19 onto the substrate 8,the support element moves along the direction along which the lamina 19has to be deposited on the substrate 8 to obtain a first arm, or a firstportion of arm of the dipole antenna. When the first arm, or portion ofarm, has been completed, in order to obtain a second arm, or portion ofarm, of the dipole antenna, the support element of the substrate 8 ismoved along the new direction along which said second arm, or portion ofarm, is to be oriented and the assembly comprised of the reel 18, thepressing roller 22 and the cutting device 23 is rotated around an axisperpendicular to the surface of the substrate 8 and passing through thepoint where the pressing roller 22 presses the lamina 19 on thesubstrate 8, so that the lamina 19 unwinding from the reel 18 is alignedalong said new direction. A similar procedure is used to realizeantennas of any shape made of wire 19. This method allows a plurality ofantennas to be realized simultaneously on the substrate 8, by providinga plurality of assemblies comprised of reel 18, pressing roller 22,cutting device 23, each of which is capable of rotating around said axisperpendicular to the surface of the support element (FIG. 7). Ingeneral, the support element and the assembly, or each assembly,comprised of the reel 18, the pressing roller 22 and the cutting device24 must be planned in such a way as to be capable of rotating withrespect to one another around an axis perpendicular to the surface ofthe support and positioned on the point of contact of the lamina 19 withthe substrate 8.

FIG. 9 illustrates another example of realization of the methodaccording to the invention, in which a face of the metallic lamina 19 issmeared with a pressure sensitive adhesive substance, that is asubstance that activates when the lamina 19 is presses onto thesubstrate 8 by the pressing roller 22. The face of the lamina opposed tothe face on which the adhesive substance has been smeared is protectedby an anti-adhesive film, in order to prevent the turns of the lamina 19on the reel 18 from adhering to each other. The anti-adhesive film isre-wound on a collecting roller 25, after the lamina 19 has beenseparated from the film and deposited on the substrate 8.

FIG. 10 illustrates a further example of realization of the methodaccording to the invention, particularly suitable for making on a singlesubstrate 8 a plurality of dipole antennas having rectilinear arm, likethe antenna A in FIG. 11.

In this example of realization, the assembly comprising the reel 18, thepressing roller 22 and the cutting device 23, is kept stationary, whilethe substrate 8 is moved under said assembly, for instance by unwindingthe substrate from a first reel 26 and re-winding it on a second reel27. On the reel 18 a plurality of laminas 19 of electrically conductivematerial may be wound. The laminas 19 are arranged in such a way as tobe parallel with each other when they are unwound from the reel 18. Asan alternative, a plurality of reel 18 arranged side by side, on each ofwhich a lamina 19 is wound, may be provided, each reel being operativelyassociated with a respective pressing roller 22 and a respective cuttingdevice 23. In this way it is possible to simultaneously deposit and fixa plurality of stretches of lamina 19 on the substrate 8, thus obtaininga plurality of dipole antennas A with rectilinear arms in a singleproduction phase. Downstream the assembly comprised of the reel 18, thepressing roller 22 and the cutting device 23, are arranged in series adepositing device 28 for depositing, between the two arms of the dipoleantenna A, a modular element EM (FIG. 12) on which a microchip ismounted, and a soldering device 29 to electrically connect by solderingthe modular element EM and, thus, the microchip MC to the arms of thedipole antenna A. The modular element EM with the microchip MC is usedto make any type of transponder, such as, for instance, the transponderswith dipole antennas B, C, D shown in FIGS. 13, 14, and 15, or eveninduction transponders. The arms of the dipole antennas B, C, D,respectively B1 b, B2 b, B1 c, B2 c, B1 d, B2 d, are connected with eachother by means of the modular element EM thus obtaining the electricalconnection between the two arms of the dipole antenna and the microchipMC.

Likewise, the ends of an antenna of an induction transponder areconnected with each other by means of a modular element EM.

In the practical embodiment, the materials, the dimensions and theconstructional details can be different from those indicated, but betechnically equivalent to them without thereby departing from the scopeof the invention defined by the claims.

1. An apparatus for making an antenna for wire transponders ofelectrically conductive material, comprising: a support element defininga plane for supporting a substrate, said support element being movablealong three directions parallel to three axes of a three-dimensionalCartesian coordinate system; and a plurality of depositing devices, eachdepositing device of said plurality of depositing devices beingconfigured for depositing a wire on said substrate placed on saidsupport element, each depositing device of said plurality of depositingdevices being capable of rotating around an axis perpendicular to saidplane, each depositing device of said plurality of depositing devicescomprising a container supplied with an adhesive substance, a wirepassing through said container before being deposited on said substrate,wherein each depositing device of said plurality of depositing devicescomprises a guide element for guiding said wire inside said container,and a dispensing element for guiding said wire outside said containerfor subsequent depositing on said substrate.
 2. The apparatus accordingto claim 1, wherein each depositing device of said plurality ofdepositing devices is movable along a direction parallel to said axisperpendicular to said plane.
 3. The apparatus according to claim 2,further comprising a support structure provided with a pair of uprightsconnected above by at least one crosspiece, said plurality of depositingdevices being associated with said at least one crosspiece.
 4. Theapparatus according to claim 2, further comprising a support structureprovided with a pair of uprights and a plurality of crosspiecesinterconnecting said pair of uprights, each depositing device of saidplurality of depositing devices being associated to each crosspiece ofsaid plurality of crosspieces.
 5. The apparatus according to claim 2,further comprising a support structure provided with a pair of uprightsand a crosspiece interconnecting said pair of uprights, said pluralityof depositing devices being associated to said crosspiece, said supportstructure being provided with at least one further crosspieceinterconnecting said pair of uprights, said apparatus comprising atleast one further plurality of depositing devices associated to said atleast one further crosspiece, each depositing device of said furtherplurality of depositing devices being configured for depositing a wireon said substrate placed on said support element.
 6. The apparatusaccording to claim 1, wherein said support element is fixed to a firstsliding element movable along a direction substantially parallel to afirst axis of said three-dimensional Cartesian coordinate system.
 7. Theapparatus according to claim 6, wherein said first sliding element isassociated with a second sliding element movable along a directionsubstantially parallel to a second axis of said three-dimensionalCartesian coordinate system.
 8. The apparatus according to claim 7,wherein said second sliding element is movable along a directionparallel to a third axis of said three-dimensional Cartesian coordinatesystem.